In the face of high staffing costs, uncertain patient arrivals, and patients unsatisfied with long wait times, staffing of medical emergency departments (EDs) is a vexing problem. Using empirical data collected from t...
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In the face of high staffing costs, uncertain patient arrivals, and patients unsatisfied with long wait times, staffing of medical emergency departments (EDs) is a vexing problem. Using empirical data collected from three active EDs, we develop an analytic model to provide an effective staffing plan for EDs. Patient demand is aggregated into discrete time buckets and used to model the stochastic distribution of patient demand within these buckets, which considerably improves model tractability. This model is capable of scheduling providers with different skill profiles who work either individually or in teams, and with patients of varying acuity levels. We show how our model helps to balance staffing costs and patient service levels, and how it facilitates examination of important ED staffing policies.
Due to the gradual increase in maritime cargo volume, exhaust fumes from the maritime industry have become a concern of various sectors of society. In particular, because of their proximity to human habitation, emissi...
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Due to the gradual increase in maritime cargo volume, exhaust fumes from the maritime industry have become a concern of various sectors of society. In particular, because of their proximity to human habitation, emissions from docked ships are a serious health hazard. Shore power, as a promising approach to reducing ship emissions in port areas, has drawn attention from govern-ments, industries, and academia. This paper reviews studies of shore power's economic challenges from the perspective of ship owners, port authorities, and governments. The basic models roughly summarize the costs of shore power for different interested parties. In addition, some technical reports and governmental studies of shore power are reviewed. This paper provides scholars in-terested in this area with a systematic review of current research on shore power. Research oppor-tunities that are worth investigating and the potential forces driving the popularization of shore power are identified. We hope that the review helps to increase research on this topic.
On présente ici une seconde version du programme d'admissibilité (securad)mis au point au cnet. Ce programme permet de router au coût minimal plusieurs milliers de demandes (exprimées en circui...
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Two-sided manufacturing-as-a-service (MaaS) marketplaces connect clients requesting manufacturing services to suppliers providing those services. The matching mechanism that allocates clients' orders to suppliers ...
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ISBN:
(纸本)9780791887240
Two-sided manufacturing-as-a-service (MaaS) marketplaces connect clients requesting manufacturing services to suppliers providing those services. The matching mechanism that allocates clients' orders to suppliers is a key design parameter of the marketplace platform. The platform might perform an allocation to maximize its revenue or optimize for social welfare of all participants. However, individual participants might not get maximum value from their match and reject it to form matches themselves (called blocking groups), thereby bypassing the platform. This paper considers the bipartite matching problem in MaaS marketplaces in a dynamic environment and proposes two matching solutions that limit the formation of blocking groups. Matching is based on non-strict, incomplete and interdependent preferences of participants over contracts, enabling negotiations between both sides. Simulations are used to test the mechanisms in a 3D printing services marketplace and evaluate the impact of stability on its performance. It is found that stable matching results in small degradation in social welfare of the marketplace but significantly better outcomes in terms of stability. Unstable matchings introduce anarchy into the marketplace with participants rejecting its allocation leading to performance poorer than stable matchings.
Facilities location is a strategic decision in supply chain design since it affects products and information flows through all the echelons. In urban contexts, facilities location is even more important because it sha...
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Facilities location is a strategic decision in supply chain design since it affects products and information flows through all the echelons. In urban contexts, facilities location is even more important because it shapes both the distribution activities and urban landscapes. In addition, changes in facilities location patterns have caused non-intended externalities such as congestion, emissions, noise, among others. We present a non-linear programming model to establish optimal facilities location in urban areas, modelling the city as a transportation network and considering congestion into the objective function. To solve the model, we use a piecewise linear optimization, which allows to obtain an optimal solution. Copyright (C) 2020 The Authors.
Energy storage technologies are essential to decouple the production and consumption of electric energy in terms of time. The rapidly rising penetration of volatile renewable energy sources and growing market shares o...
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ISBN:
(纸本)9781538682180
Energy storage technologies are essential to decouple the production and consumption of electric energy in terms of time. The rapidly rising penetration of volatile renewable energy sources and growing market shares of electric vehicles increase the demand for efficient batteries with state of the art management systems. For elaborate applications with (predictive) power dispatch optimization at runtime, e.g. complex microgrids with participation in energy markets and ancillary services, reliable models and fast algorithms are crucial. To develop these, mathematical models capturing the dynamics of battery behavior over time are needed. This paper proposes a linear approximation approach for nonlinear cyclic aging dynamics of batteries that can easily be integrated into existing dispatch optimization software based on Mixed-Integer Linear programming.
Environmental/economic dispatch is a fundamental issue in power system operations as it deals with the scheduling of the generating output among available units for simultaneous minimization of fuel cost and emission ...
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Environmental/economic dispatch is a fundamental issue in power system operations as it deals with the scheduling of the generating output among available units for simultaneous minimization of fuel cost and emission output, two objectives that collide. Furthermore the violation of specific constraints must be avoided. In this paper, environmental/economic dispatch is solved applying a new meta-heuristic optimization method, namely flower pollination algorithm. The proposed method is inspired by the pollination process of flowering plants with Levy flight to imitate the movement of insect pollinators. The multi-objective environmental/economic dispatch problem can be described by polynomial objective functions and converted into single-objective using weighted sum method that produces non-dominated solutions. The most satisfactory solution is chosen according to a decision maker that is based on fuzzy set theory. Effectiveness of the proposed approach is examined on two test systems. The first system comprises three generating units while the second one is a six-unit system. Numerical results obtained are compared to those obtained by other modern optimization methods. The proposed flower pollination algorithm seems to be a promised optimization technique as it provides fast and efficient solutions.
A rigorous mathematical programming framework for the scheduling of multipurpose batch plants operated in a cyclic mode is presented. The proposed formulation can deal with batch operations described by complex proces...
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Flexible manufacturing systems (FMS) are generally set up to process a wide variety of parts with low to medium volume demand. The loading problem in FMS is a short-term decision issue, which addresses the simultaneou...
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Flexible manufacturing systems (FMS) are generally set up to process a wide variety of parts with low to medium volume demand. The loading problem in FMS is a short-term decision issue, which addresses the simultaneous processing of a set of different parts in an efficient manner on capital-intensive resources. This study focuses on cyclic schedules in loading pallets carrying groups of identical parts to CNC machining centers. A predefined stream of pallets fixtured for different part types is repeatedly supplied to every CNC machine in cycles. Moreover, a limited number of pallets have to be shared among the cycles of machines to keep utilization and the overall throughput rate at acceptably high levels. The solution approach is an integrated mix of optimization and simulation methodologies. The validation of the model is based on data from past 6 months of operation. Comparisons are made retrospectively. (C) 2002 Elsevier Science Ltd. All rights reserved.
The purpose of this paper is to compare and contrast the modeling capabilities of seven algebraic modeling languages (ML) available today, namely, AMPL, GAMS, LINGO, LPL, MPL, PC-PROG and XPRESS-LP. In general, these ...
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The purpose of this paper is to compare and contrast the modeling capabilities of seven algebraic modeling languages (ML) available today, namely, AMPL, GAMS, LINGO, LPL, MPL, PC-PROG and XPRESS-LP. In general, these MLs do an excellent job of providing an interface with which the modeler can specify an algebraically formatted linear program (LP). That is, each ML provides a substantial improvement in time and convenience over the matrix generator/report writers of the last few decades. Further, each of the MLs provides: (1) significant flexibility in model specification, instantiation and modification, (2) effective and efficient conversion from algebraic to solver format, and (3) an understandable and, for the most part, self-documenting model representation. In addition, each of the MLs is constantly being updated and upgraded to provide additional capabilities sought by practitioners and users. However, as shown in the fifteen tables provided in the body of this paper, each ML has its own set of competitive advantages. For example, the most integrated environments (i.e. those integrating the modeling language with a full-screen editor, data import capabilities and a solver) are provided by LINGO and PC-PROG. The most user-friendly interfaces are provided by MPL and PC-PROG, both of which provide window-based interfaces to create models and pop-up windows to display error messages;MPL also uses pull-down menus to specify various operations, whereas PC-PROG uses function keys for operational control. Package costs are led by a current (March, 1991) introductory offer from LINGO. Modeling effectiveness, especially with respect to flexibility in specifying arithmetic statements, is led by GAMS and LPL. Model compactness, as measured by the number of lines required to specify a model, is led by AMPL, LPL, MPL and PC-PROG;LPL, MPL and PC-PROG also provide context sensitive editors which automatically position the cursor where the error was detected. And finally, the m
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